1. Field of the Invention
The present invention relates to a screen printing method and a holding table for a plate to be printed used for the method.
2. Description of the Prior Art
A screen printing is so structured as to move a squeegee in a state of bringing a screen into contact with an upper surface of a plate to be printed such as a printed plate board and the like or setting the screen slightly apart therefrom and apply a printing agent such as a creamed solder and the like to the plate to be printed, thereby performing a printing.
Further, during the process, the screen is separated from the plate to be printed after applying the printing agent. In this case, the screen is conventionally wholly lifted up to an immediately upper direction and all the surface is separated simultaneously from the plate to be coated.
However, when all the surface is simultaneously separated as mentioned above, there is a case that the printing agent within a through hole of the screen is left within the through hole without being released out over the printed plate board, especially at the moment the screen is separated at a center portion thereof, depending upon a degree of a viscosity of the printing agent. In this case, an uneven coating of the printing agent on the plate to be printed is generated, so that a problem that a lack of pattern is generated. For this reason, in order to peel off the uneven printing agent conventionally, a peeling operation is performed for ten and some minutes.
Therefore, a lot of producing time is required by the time of completion, and this greatly causes to increase a cost of a product.
The present invention is made by taking the points mentioned above into consideration, and an object of the present invention is to provide a screen printing method structured so that a printing agent within a through hole of a screen may smoothly and completely release out when separating the screen from a plate to be printed, thereby preventing a uneven coating of the printing agent from generating.
Another object of the present invention is to provide a screen printing method structured so as to move a squeegee with a proper interval between a screen and a plate to be printed, in which a printing can be performed by keeping the same interval from the first to the last printing operation.
Still further, the other object of the present invention is to provide a holding table for a plate to be printed which is so structured as to efficiently perform the screen printing method mentioned above.
In accordance with a first aspect of the present invention, there is provided a screen printing method, in which at a time of applying a printing agent to a plate to be printed by a movement of a squeegee, the plate to be printed is gradually separated from said screen and from one side of the screen to the other side thereof step by step during a movement of the squeegee to a movement finishing end.
Further, in accordance with a second aspect of the present invention, there is provided a screen printing method, in which at a time of applying a printing agent to a plate to be printed by a movement of a squeegee, the plate to be printed is gradually separated from said screen and from one side of the screen to the other side thereof step by step after the squeegee reaches a movement finishing end.
Still further, in accordance with a third aspect of the present invention, there is provided a screen printing method which is so structured as to move a squeegee at a proper interval between a screen and a plate to be printed, in which at a time of applying a printing agent to a plate to be printed by a movement of a squeegee, the plate to be printed is set below the screen in an inclined manner so that a movement starting side is most apart, and a movement finishing side of the squeegee of the plate to be printed is gradually descended in correspondence to a moving speed of the squeegee to thereby always keep printing at the same interval.
Furthermore, in accordance with a fourth aspect of the present invention, there is provided a screen printing method which is so structured as to move a squeegee at a proper interval between a screen and a plate to be printed, in which at a time of applying a printing agent to a plate to be printed by a movement of a squeegee, the plate to be printed is set below the screen in an inclined manner so that a movement starting side is most apart, and the plate to be printed is gradually descended while keeping an angle of incline in correspondence to a moving speed of the squeegee to thereby always keep printing at the same interval.
Moreover, the screen printing method in accordance with the first, second and third aspects mentioned above of the prevent invention can be efficiently realized by a holding table for a plate to be printed comprising a supporting body stood on an end on a table plate, a holding plate setting a plate to be printed on a surface thereof, an end of the holding plate being pivotally attached to an upper end of said supporting body in such a manner as to freely incline, and said holding plate being gradually inclined from a horizontal state at a predetermined speed via proper means.
Further, the holding table for the plate to be printed may be made by the following concrete structure. Accordingly, there is provided a holding table for a plate to be printed, comprising a table plate, a supporting body stood on an end on said table plate, a holding plate setting the plate to be printed on an upper surface thereof and having an end pivotally attached to an upper end of said supporting body in such a manner as to freely incline, a link having one end side pivotally connected to a lower surface in a side of a free end of said holding plate and the other end side pivotally connected to a moving table, the moving table mounted in such a manner as to freely move in a direction of attaching to and detaching from said supporting body, a driving plate adhered to said moving table and having a screw with which a screw shaft is engaged, and a reversible driving motor adhered on said table plate and making the screw shaft connected to an axis of rotation thereof to engage with the screw of said driving plate.